Glad to hear that you are moving back.
Don't know about cooling as I haven't seen an indoor temperature greater than 29'C and it was 45'C outside that day...
Last summer was a shocker...
For a left of centre idea about heating, you can try the system I use here. Hard to retrofit, but easy to use.
The hot water system has a 400L header tank which is heated by a combination of:
- solar hot water panels (ouch! - very hot for most months other than June - August);
- Wet back on the firewood box (after a day of heating the water is toasty hot); and
- If I had more faith in the off grid system, I could have added an electric element to the header tank - A great idea for all of that PV solar energy I'm currently losing. It works like a fish tank heater.
The water from the header tank is pumped around to hydronic radiators which can be switched off and on as needed. Oh yeah, they get hot and it is a very pleasant heat.
LPG is a no go for a house due to the sheer expense. When I rented whilst I was building this house, they had a huge LPG tank (about $700 to fill - many years ago too) and an LPG fuelled central heating system. The LPG supply company told me not to set the temperature in the house above 16'C degrees or I'd empty the bottle in only a few weeks....
I didn't run that heater once and oh boy, was that house cold in winter and hot in summer. Winter meant sleeping under two heavy doona's as it was little above freezing.
The firebox runs continuously here during winter, but then the outside temperature doesn't get into double digits either. Because the house is heavily insulated the heater uses stuff all timber during a year. Run it hard for the first load and then back it off and just leave the combustion ticking along.
My wife can get the firebox started - no problem, but I keep all of the systems here as simple as possible and there is dry kindling, small logs, medium logs and larger logs all available under cover.